Abstract

Gaussian modes of arbitrary large section have been experimentally produced by using Gaussian reflectivity mirrors in unstable resonators. The Cassegrain configuration has appeared particularly attractive because it produced a collimated output beam and improved the far-field brightness.¹ The transverse energy distributions of the beam inside the cavity in the near field and in the far field have been investigated. The introduction of a hard aperture in the cavity did not significantly deteriorate the optical quality of the beam as long as the aperture diameter was > 1.4 times the beam diameter (at 1/e of the central intensity). With smaller apertures, the far-field pattern broadened, remaining free from secondary rings. With a large enough gain section, it has been observed that a misalignment of a cavity mirror did not affect the width or the Gaussian form of both the intracavity and the far-field energy distributions.

© 1985 Optical Society of America